Population structure of a predatory beetle: the importance of gene flow for intertrophic level interactions

Abstract

Migration and gene flow of natural enemies play an important role in the stability of predator-prey interactions and community organization in both natural and managed systems. Yet, relative to that of their herbivorous insect prey, the genetic structure of natural enemy populations has been little studied. We present evidence that populations of the predatory coccinellid beetle Coleomegilla maculata (Coleoptera: Coccinellidae), are not genetically subdivided and that levels of gene flow among these populations are extremely high. Furthermore, in the same geographical area, gene flow of C. maculata was significantly (one order of magnitude) greater than that of an abundant prey species, the Colorado potato beetle Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). The high mobility of this natural enemy relative to the insect herbivores on which it feeds may contribute to its effectiveness as a biological control agent in agricultural systems.

Effects of Varying Weed Communities in Corn on European Corn Borer, <I>Ostrinia nubilalis</I> (Hübner) (Lepidoptera: Crambidae), Oviposition, and Egg Mass Predation

“…Nault and Kennedy (2000) reported that migration occurs among several crops over the course of a season. Coll et al (1994) used allozyme frequencies to estimate gene ßow among populations and concluded that C. maculata is highly mobile. Thus, these insects may be freely moving among treatments even where plots are quite large, as in our study.…”

Comparative Geographic Structures of Two Parasitoid‐host Interactions

“…Price (1980) suggested that population subdivision is a major consequence of the parasitic lifestyle and should be typical for both parasitoids and phytophagous insects. Population subdivision has been demonstrated for many species of phytophagous insects, but fewer studies have been conducted for natural enemies such as parasitoids (ColI et al 1994). Specialist paras itoids may be more likely to exhibit population subdivision given that they usually have lower population sizes than their hosts (Godfray 1994).…”

Population genetics of an opportunistic parasitoid in an agricultural landscape

“…Predatory lady beetles (Coleoptera: Coccinellidae) are the only natural enemies whose population structure has been studied extensively (Krafsur et al, 1992(Krafsur et al, , 1995Steiner & Grasela, 1993;Coll et al, 1994). These studies employed allozyme electrophoresis to examine gene flow and the main conclusion drawn from each study was that the lady beetle population was not subdivided, even between states in some cases.…”